The current rule for starting treatment of HIV infection is to combine members from different classes of anti-HIV drugs, such as 2 nucleoside reverse transcriptase inhibitors (NRTIs) and either a PI or a nonnucleoside reverse transcriptase inhibitor (NNRTI). However, these combinations can be complicated and difficult to take, can cause a number of side effects, and may become ineffective. Combinations that are simpler, better tolerated, and more effective are needed. Because PIs can cause long-term side effects and because HIV can become resistant to many of them at the same time, anti-HIV combination treatments that do not use PIs are being tested.